JPH07112821B2 - Vehicle steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Outline of the Disclosure) The present invention has a mechanical power transmission means between a steering operator operated by a driver and a steering mechanism for steering wheels of a vehicle. A vehicle steering apparatus of a non-type is provided with a safety means for preventing the wheels from being steered against the driver's intention to operate.

(Field of Industrial Application) The present invention relates to a vehicle of a type having no mechanical power transmission means between a steering operator operated by a driver and a steering mechanism for steering wheels of the vehicle. Regarding the steering system, the number of steering wheels is 1.
The invention can be applied to a vehicle having only one set, or the main steering wheel is connected to the steering operation device and only the auxiliary steering wheel (for example, rear wheel) may be applied.

(Prior Art) A steering apparatus for an automobile generally has a mechanical power transmission mechanism between a steering operator and a wheel steering mechanism. It is also known to apply an auxiliary force to the power transmission mechanism to reduce the steering operation force by the driver.

In Japanese Utility Model Laid-Open No. 60-49072, a hydraulic cylinder provided on the rear wheels is driven by a control valve that is controlled according to a signal from a steering wheel front wheel steering sensor, and a piston rod is neutralized by driving the hydraulic cylinder. It is shown that the piston rod is locked when returning to the position.

(Problems to be Solved by the Invention) In the conventional steering device, since the mechanical power transmission mechanism that connects the steering operator and the steering mechanism is present, the steering mechanism is opposed to the driver's operation. While there is an advantage that it does not operate, there are restrictions in vehicle design regarding the arrangement of the power transmission mechanism.

Further, in the structure in which the steering mechanism of the vehicle is driven only by the hydraulic control valve, there is a problem that the operation of returning to the neutral position cannot be performed when the drive system fails. It was

Therefore, an object of the present invention is to provide a device that enables steering without using the power transmission mechanism as described above and that prevents a malfunction of the steering mechanism.

(Means for Solving Problems) Therefore, the present invention provides a steering operation device that is operated by a driver and generates a signal representing a desired steering angle of a vehicle, and a mechanical device that is mechanically independent of the steering operation device. A steering mechanism that steers the wheels of the vehicle; drive means that drives the steering mechanism to steer the wheels in response to a signal representing a desired steering angle from the steering operator; When the drive of the steering mechanism is invalidated, the steering mechanism returning means for returning the steering mechanism to a predetermined position, and a fixing means for fixing the steering mechanism at the predetermined position are provided. To do.

(Operation and Effect) With this configuration, if the driver operates the steering operation device,
A signal indicating the desired steering angle is generated from the steering operation device, and the driving means receives this signal and drives the steering mechanism. Therefore, the steering operation device and the drive means need only be provided with signal transmission means, and no mechanical power transmission mechanism is required.

When a failure occurs, the drive means stops receiving the signal from the steering operator to drive the steered mechanism, and in this state, the steered mechanism is operated without the driving force from the drive means. It is returned to a predetermined position by the rudder mechanism returning means and further fixed. Therefore, even if a failure occurs in the control system of the steering device, the drive means of the steering mechanism, etc., the wheels are not undesirably steered at all, and the dangerous state of the vehicle and other transportation means etc. It is possible to suppress the interference.

(Embodiment) FIG. 1 shows an outline of a front wheel steering system for a vehicle to which the present invention is applied. The steering wheel 1 is rotatably held on the vehicle body by a mounting member 3 so as to apply a rotational force to the shaft 2 connected thereto. The shaft 2 is also coupled via a torque sensor 5 to a motor 4 for applying a steering reaction to the steering wheel 1, and an angle sensor 6 for detecting the rotation angle of the shaft 2 is attached to the rotation shaft of the motor 4. Has been.

The pair of front wheels 7 and 8 form the steered wheels of the four-wheel vehicle,
The control rods 10 and 11 extending to both ends of the steering mechanism 9 are turned together. The steering mechanism 9 has a power cylinder assembly 13 including a power piston 12 connected to control rods 10 and 11, as shown in detail in FIG. The power cylinder assembly 13 is a rack and pinion mechanism 14
Is connected to the rotating shaft 16 of the motor 15 via
The rotational force of 15 acts as a reciprocating steering force of the power piston 12.

A servo valve 18 including a torsion bar 17 is arranged between the rotary shaft 16 of the motor 15 and the rack and pinion mechanism 14, and the servo valve 18 responds to the torsion torque generated in the torsion bar 17 by an oil introducing pipe 19 And the oil discharge pipe 20 are selectively connected between both chambers of the power biston 12. The torque sensor 21 attached to the rotary shaft 16 detects the twisting torque generated during the turning as an electric signal. The rotation angle of the motor 15 is detected by the angle sensor 22 as an electric signal.

As shown in FIG. 1, the servo valve 18 is supplied with pressure oil from an oil pump driven by a vehicle engine through an oil introduction pipe 19, and the oil discharged from the servo valve 18 is discharged through a discharge pipe 20. After that, it is returned to the oil tank 24.

The motor 4 and the motor 15 are powered by the on-vehicle battery BATT as a power source and receive the electric signals from the torque sensors 5 and 21 and the angle sensors 6 and 22 to generate an output signal.
It receives the output signal from U and rotates.

In FIG. 2, a first spring 25 is stretched between a pin 26 fixed to the housing of the power cylinder assembly 13 and a pin 27 fixed to one rod 10, and a second spring 28 is formed. It is stretched between a pin 26 of the power cylinder assembly 13 and a pin 29 fixed to the other rod 11. Both springs 25 and 28 have an action of moving the power piston 12 and the rods 10 and 11 to positions where the expansion and contraction forces of the motor 15 are balanced when the motor 15 does not apply the driving force to the steering mechanism 9. Therefore, the normal motor 15 applies a driving force to the power piston 12 against the expansion / contraction force of one of the springs 25 and 28.

The power cylinder assembly 13 is provided with a fixing device 30. In the fixing device 30, a ball 33 is movably arranged in a cylinder 31 opened in a direction perpendicular to the steering rod 10 so that it can be pressed via a needle 32. A depressurizing notch 36 and a pressing protrusion 37 are provided on the cam 35 so that the needle 31 can be pressed or depressurized by a cam 35 rotated by a solenoid 34.

The rod 10 is provided with a recess 38 that faces the cylinder 31 when the steered wheels are parallel to the traveling direction, that is, in the neutral state. In the recess 38, with the ball 33 partially pushed in, the ball 33 fixes the recess 38 and the cylinder 32 to each other, whereby the rod 10 is fixed to the power piston assembly 13. .

Now, when the solenoid 34 is in the deenergized state, the cam 35 is in the position b shown by the broken line, and the pressure reducing notch 36 makes the needle 32 idle, so that the rod 10 can be driven by the motor 15. On the other hand, when the solenoid 34 is urged while the motor 15 does not apply the driving force, the cam 35 tries to rotate toward the position a in the figure.
At this time, the rod 10 is moved toward the neutral position by the springs 25 and 28, and when it reaches the neutral position,
The ball 33 is pushed into the recess 38 to fix the rod 10. As a result, the steered wheels 7 and 8 are fixed in a state parallel to the traveling direction.

The circuit configuration of the ECU shown in FIG. 1 is shown in FIG.
Generally, the rotation angle of the steering wheel 1 and the movement amount of the steering mechanism 9 have a predetermined direct proportional relationship. Therefore, the angle sensor 6
When the electrical signal output by the angle sensor 22 and the electrical signal output by the angle sensor 22 satisfy this direct proportional relationship,
It is adjusted in advance so as to have the same value.

An operation amplification circuit 39 is provided, and an electric signal indicating the steering angle of the steering wheel 1 detected by the angle sensor 6 and an electric signal indicating the rotation angle of the motor 15 detected by the angle sensor 22 are provided. . When the rotation angle of the motor 1 deviates from the above-mentioned proportional relation to the steering angle of the steering wheel, an electric signal 40 corresponding to the degree of deviation is given from the output end of the operation amplification circuit 39 to the motor drive circuit 41. .

The motor drive circuit 41 reversibly drives the motor 15 according to the value of the electric signal 40 so that the electric signal 40 falls within a preset value range, so that the steered mechanism 9 operates the steering wheel 1. It acts so as to move in conjunction with the operation angle with a predetermined correspondence.

Another operation amplification circuit 42 is provided, and the torque sensor 5
When the magnitude relationship between the torque detected by the torque sensor 21 and the torque detected by the torque sensor 21 deviates from a predetermined correspondence relationship, an electric signal indicating the degree of deviation is output to the motor drive circuit 44.
Granted to. Generally, it is desirable that part of the reaction force that the steered wheels 7.8 receives from the road surface during steering is fed back to the steered wheels 1. The operation amplification circuit 42 and the motor drive circuit 44 cooperate with each other so that the torque of the steering reaction force generated on the rotating shaft 2 is predetermined with respect to the torque of the road surface reaction force generated between the steering mechanism 9 and the motor 15. To have a correspondence of
It acts so as to apply a rotational force opposite to the steering direction to the motor 4.

The ECU also incorporates a coincidence detection circuit 45 as a safety circuit. The coincidence detection circuit 45 compares the electric signals from both the angle sensors 6 and 22, and the steering mechanism 9 determines that the steering wheel 1
When it does not have the above-mentioned predetermined correspondence with the operation angle of, the detection signal 46 is output. The detection signal 46 is applied to the motor drive circuit 41 and the solenoid 34 of the fixing device 30. When the motor drive circuit 41 receives the detection signal 46, the power supply to the motor 15 is cut off by stopping the power supply circuit, for example, and the motor 15 stops supplying the driving force to the steering mechanism 9.
Further, the solenoid 34 tries to rotate the cam 35 as described above.

Then, when the coincidence detection circuit 45 detects that the control circuit ECU is not in a normal operating state, the motor 15 causes the steering mechanism 9 to rotate.
Since no driving force is generated for the steering wheels 7, 28, the springs 25, 28 act to move the steered wheels 7, 8 to the neutral position, and when the neutral position is reached, the fixing device 30 moves the power piston 12 to the power cylinder assembly 13 Fixed to.

Thus, when the steering device does not function normally, the steered mechanism 9 is fixed in the straight traveling state, so that the steered wheels are not steered in an uncertain direction.

FIG. 5 illustrates another embodiment to which the present invention is applied. The steering wheel 1 is connected to a front wheel steering mechanism 9 via a rotary shaft 2, and if necessary, the hydraulic servo device as described in the above embodiment can be combined.

On the other hand, a drive motor 15A that reversibly applies a steering force is attached to the rear wheel steering mechanism 9A. The operation angle of the steering wheel 1 is detected by the angle sensor 6, and the control circuit ECU sends a control signal so that the turning amount of the rear wheel turning mechanism 9A represented by the rotation angle of the motor 15A has a predetermined correspondence relationship with the detected angle. To occur.

In the same manner as in the above-described embodiment, the fixing device 30A fixes the steering angle of the rear wheels in a predetermined direction when the rear wheel steering device fails to function normally in cooperation with the return mechanism by a spring (not shown).

The present invention can also be applied to a vehicle having such a mechanism that steers four wheels. As described above, in the four-wheel steering system, the vehicle speed sensor 47 for detecting the vehicle speed, the yaw rate sensor 48 for detecting the yaw rate, the changeover switch 49 for manually switching between the width-shifting mode and the turning mode, or the forward / backward traveling by the backward light lighting signal By receiving a signal from the changeover switch 50, it is possible to correct the correspondence relationship between the turning angle of the steering wheel 1 and the turning amount of the rear wheel turning mechanism 9A for each operation mode.

Needless to say, in carrying out the present invention, appropriate changes can be made within the scope of the inventive idea described in the claims.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an embodiment of the present invention, FIG. 2 is a sectional configuration diagram of a peripheral portion of a steering mechanism 9, FIG. 3 is a sectional configuration diagram of a fixing device 30, and FIG. 4 is a control circuit ECU. Block diagram of No. 5,
The figure is a schematic block diagram of another embodiment of the present invention. 1 ... Steering wheel, 6 ... Angle sensor, 7,8 ... Steering wheel, 9 ... Steering mechanism, 13 ... Power cylinder assembly, 15
...... Motor, 25, 28 …… Spring, 30 …… Fixing device.

Claims (1)

[Claims] 1. A steering manipulator that is operated by a driver to generate a signal representing a desired steering angle of the vehicle, and a steering that is provided mechanically independent of the steering manipulator and steers the wheels of the vehicle. A mechanism, drive means for driving the steering mechanism to steer the wheels in response to a signal indicating a desired steering angle from the steering operator, and disabling the driving of the steering mechanism by the drive means. A steering apparatus for a vehicle, comprising: a steering mechanism returning means for returning the steering mechanism to a predetermined position when the above is performed; and a fixing means for fixing the steering mechanism to the predetermined position.